I have noted a few loggings of RTL with very weak signal on the old frequency 234 kHz.
I think the transmitter is operated the same way as Kalundborg on 243 kHz. When the transmitter is switched off the exciter is still active. The power of the signal from the exciter is attenuated when it passes through the switched off power stage. But a small amount is still radiated. In 2015 Terecom estimated that 1 – 5 Watts were radiated as an open carrier on 243 kHz. Modern high power transmitters are operated in that way.
Karl-Erik Stridh (2023-01-05)